Lara Croft and the Guardian of Light is an ambitious project. As a non-canon entry in the Tomb Raider franchise, the game breaks with the series history in myriad ways, a move thats sure to surprise and maybe infuriate some fans. But somehow, the developers pulled it off. This is a fun-packed action/adventure title thats well worth its $15 price tag.

Franchise devotees will realize why the official Tomb Raider name was left off this title: the gameplay has been totally revamped. Lara still does what shes always done. Like a scantily-clad female Indiana Jones, she grapples and jumps between platforms, shoots supernatural beings, and collects ancient relics while wearing short shorts and a skimpy tank top. The view and controls, however, are completely different. Gone is the over-the-shoulder camera, replaced by a fixed, floating one that provides an isometric view. The controls, meanwhile, make the game feel more like Geometry Wars than like your standard third-person shooter; you move with the left joystick, draw your weapons and aim them with the right joystick, and fire with a trigger. Other buttons let you select guns, jump, and access your inventory. The setup takes some getting used to, but it gives the action a great arcade feel.

You can play by yourself or with a partner, but the co-op play is the games real high point. (For the time being, co-op is local-only on Xbox 360. Online co-op will be added via a free update September 28, to coincide with the games release on PSN and Windows.) The second player takes on the role of the 2,000-year-old Mayan warrior Totec, also known as the Guardian of Light. Lara has her trademark guns and grapple, while Totec carries spears, which serve both as weapons and as convenient tools that you can throw into a wall and jump on. Totec also has a shield that Lara can use as a platform; if he jumps while shes standing on it, Lara can reach even higher.

Not surprisingly, the puzzles in the co-op mode require plenty of teamwork. Youll handle everything from standard switch-flipping problems to more innovative puzzles that require rolling large globes around and manipulating the environment in subtle ways. Between puzzles, you fight waves of enemies and bosses, which, on medium difficulty, are easy until about halfway through the game.

Rather than torture single-player gamers with a bumbling and glitchy A.I. partner (is there any other kind?), the developers simply redesigned all the levels so that Lara, with some extra abilities (for example, Totecs spear), can complete them on her own. Without the teamwork element, the puzzles are a bit less inventive, but the developers did a great job of rearranging them so that they remain challenging and reasonably interesting.

When you find relics and artifacts, you can equip them to give your character special powers. The relic system in particular is interesting; you cant use relics until youve filled a meter by killing enemies without taking damage. The meter resets to zero as soon as you take a hit. You also have a traditional health bar as well as an ammo bar that depletes at different rates depending on which weapon youre using. (Totecs spear and Laras dual pistols have infinite ammo.)

The fifteen levels here are straightforward and linear; the first time through, it takes only five to seven hours to finish the game, though you can spend more if you want to beat both the single-player and multiplayer. (Wed argue its probably not worth it, especially if you start with the better co-op levels.) However, theres replay value galore, and completionists will be consumed for days. Each level features optional item rooms, as well as achievements, which challenge you to complete the level within a certain time limit or not take damage during a certain section, for example. The levels are also riddled with collectibles, including red skulls, gems, more than sixty artifacts and relics, extra costumes, and more than twenty-five different weapons.